Long life regulated sea water battery

ABSTRACT

A sea water battery is housed within a container which is open to sea water at the bottom and which has a controllable valve for allowing gas to escape from the top. The opening and closing of the valve are actuated, respectively, by predetermined lower and upper battery voltage limits so as to control the amount of water within the container to thereby regulate the output voltage.

United States Patent Joseph M. Marzolf Falls Church, Va. 819,875 Apr.28, 1969 Sept. 21, 1971 The United States of America as represented bythe Secretary of the Navy inventor Appl. No. Filed Patented AssigneeLONG LIFE REGULATED SEA WATER BATTERY 6 Claims, 1 Drawing Fig.

[1.8. CI. l36/l00, 136/178 Int. Cl "01m 17/00 Field of Search... l36/83,I00, 178

[56] References Cited UNITED STATES PATENTS 2,781,413 2/1957 Lueningl36/l00 X 3,012,087 l2/l96l Billiard et al. 136/100 X PrimaryExaminer-Donald L. Walton Attorneys-R. S. Sciascia and A. L. Branning1:: I 4 a M2: I i I l i l I ll LONG LIFE REGULA'IED SEA WATER BATTERYSTATEMENT OF GOVERNMENT INTEREST The invention described herein may bemanufactured and used by or for the Government of the United States ofAmerica for governmental purposes without the payment of any royaltiesthereon or therefor.

BACKGROUND OF THE INVENTION The invention relates generally to a seawater battery or to those types of batteries in which the anode isconsumed or eroded in the process of providing an output voltage. Suchbatteries commonly employ magnesium-base alloy metals. More specificallythe invention provides a means for controlling the rate at which seawater is allowed to come in contact with the consumable battery anodethereby resulting in an extended life and an output voltage which can bemaintained between preselected limits.

Magnesium anode sea water batteries provide an attractive power sourcefor small, isolated marine installations because of their low cost andindefinite shelf life. The life of a battery, for a given load, dependsupon the thickness of the magnesium anode which is consumed and theclogging that takes place between the electrodes. These factors impose apractical limitation on the life of the battery. Prior suggestedtechniques for overcoming these disadvantages have relied uponsuccessive activation of conventional batteries in sequence. However themechanical problems of maintaining seals intact over long periods oftime and then mechanically opening them cause significant practicaldesign problems which have not been adequately solved to date. It wouldtherefore be highly desira ble to have a battery which provides a meansfor automatically removing the clogging material from the vicinity ofthe electrodes and in addition allows for a gradual exposure of theanode surface to the sea water dependent on the output voltage of thebattery.

OBJECTS O THE INVENTION SUMMARY OF THE INVENTION These and other objectsand advantages of the invention are realized by a battery placed withina bottomless container having a normally opened controllable valvelocated in the top part thereof. When the battery is immersed in thesea, water will enter the bottom of the container, actuating the batteryand forcing the air out through the open valve. As the water rises, theactive area of the battery increased and the terminal voltage rises.When this voltage increases to the operating point of the valve, it willclose, thus trapping the remaining gas in the top of the container andpreventing further flow of water into the bottom. With the valve sealed,the battery voltage will decrease slowly as the magnesium in contactwith the water is eroded and also because the hydrogen produced in thereaction increases the pressure in the container and slowly forces thewater out the bottom. When the voltage drops to the lower limit, thevalve opens allowing some of the entrapped gas to escape and additionalwater to enter from the bottom. The activation of additional batteryarea causes the terminal voltage to rise until the valve closes and thecycle repeats.

Thus with each successive cycle some magnesium will be eroded from thebottom and the water will slowly rise activating new area. When thewater reaches the top, after many cycles, the magnesium will becompletely consumed and the battery life will end. During the life ofthe battery, the compounds normally causing clogging will be free todrop out the bottom and will not interfere with the operation of thebattery.

BRIEF psscRiPTioN or THE DRAWING The invention will be described morefully in connection with the embodiment shown in the single drawingwhich illustrates the operating parts of the battery, container andvalve mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, theseawater battery constructed in accordance with the invention consistsof a battery 2 having a consumable magnesium anode 4 and an inert metal,nickel for example, cathode 5 and affixed in a vertical position withina container 3 that is gastight on all sides and the top when valve 9 isclosed, but open to the ambient. sea water 10 at the bottom. An opening11 is formed in the top of the container 3 which is capable of beingsealed by a valve 9 operated directly from the battery voltage by asolenoid 7. The valve 9 is normally open but is designed to close whenthe voltage output from the battery rises to a first preselected valueand to open when the battery voltage drops to a second preselected lowervalue. Solenoid 7 is operated by pilot relay 6 which opens and closescontacts 8. In this manner the output of the battery is maintainedbetween selected limits by controlling the surface area of the anode incontact with the sea water.

The operation of the battery control system of the invention will now beexplained in more detail. When the battery and its container areimmersed in the sea, water will enter the bottom of the container 3thereby initiating a chemical reaction which produces a potentialdifference between the electrodes 4 and 5. The chemical operation of asea water battery is well known in the art and will not be explained ingreater detail here. Contacts 8 are normally closed by means of pilotrelay 6 thereby allowing the terminal voltage of the battery to beapplied across solenoid 7 which keeps the valve 9 out of contact withthe opening II. The valve 9 is spring biased into closing engagementwith the aperture 11 when the solenoid 7 is deenergized. The solenoid 7however is selected to operate at a low battery voltage so that a shorttime after the device is immersed in sea water it becomes energized andholds the valve 9 out of engagement with the vent 11. Pilot relay 6 ischosen such that it opens the contacts 8 at a preselected first highvoltage and closes them at a second preselected lower voltage. It isthis action of the relay 6 which allows the battery voltage to bemaintained between preselected limits. While the contacts 8 are closedair escapes from the: container through vent l1 and past the valve 9. Asthe air escapes the sea water will rise in the container and theterminal voltage of the battery will increase to a point to actuaterelay 6 and open the contacts 8. This action will deactivate thesolenoid 7 and allow the spring-biased valve 9 to engage the opening 11in the top of the container. Since no more air can escape through theopening the sea water ceases to rise in the container. in this state thebattery voltage will decrease slowly due to the erosion of the magnesiumanode and also because of the internal pressure of the container causedby the production of hydrogen gas as a result of the chemical reaction.When the battery voltage reaches the point at which relay 6 isdeenergized the contacts 8 will close thereby allowing air to againescape from the container which results in the sea water rising intocontact with a larger surface area of the anode and allowing the batteryvoltage to again rise, thereby repeating the aforedescribed cycle.

Thus with each successive cycle some magnesium will be eroded from thebottom and the water will slowly rise activating a new area. When thewater reaches the top after many cycles, the magnesium will becompletely consumed and the battery life will end. During the life ofthebattery, the compounds normally causing clogging will be free to dripout of the bottom and will not interfere with the operation of thebattery. This removal of clogging material and gradual exposure of theconsumable anode to the sea water makes it possible to design a batteryhaving a lifetime many times greater than is possible with conventionaltype construction. It also provides a means of regulating the batteryvoltage between preselected limits.

The container can be made of a variety of materials so long as it iselectrically insulated from the battery. The device can be made to floatnear the surface or alternately can sink below the surface dependingupon the particular use to which the battery will be put. The limitswithin which the output voltage is maintained are purely a matter ofdesign choice implemented by properly selecting the operatingcharacteristics of the pilot relay. It is within the scope of theinvention to employ several pairs of electrodes within a singlecontainer or alternately to use the container itself as an electrode.The mechanical relays shown in the drawing were used merely todemonstrate the principle of operation of the invention and may beeasily replaced by solid state switching devices without departing fromthe principle of the invention. It is apparent also that the opening atthe bottom of the container can take the form of a hole situated nearrather than at the very bottom of the container, the same being true ofthe location of the aperture 11. The relays and other control means canbe located either outside of or within the container in the water tightenclosure near the top of the container.

lclaim:

l. A sea water battery comprising:

a battery cell including electrodes requiring sea water to produce avoltage output;

a container enclosing said cell but open to sea water through a lowerpart and including an aperture through an upper part thereof;

means for regulating the surface area of said electrodes in contact withsea water, including a valve engaging said aperture and actuating meansfor continuously opening and closing said aperture to regulate saidvalve in response to said voltage output.

2. The battery of claim 1 wherein said actuating means is coupled tosaid valve in a manner to vent gases evolved from said battery cell atpreselected voltage outputs.

3. The battery of claim 1 wherein said container is shaped to entrapgases in its upper part adjacent said aperture.

4. The battery of claim 2 wherein said actuating means includes at leasttwo electrically responsive switches.

5. The battery of claim 1 wherein said electrodes are consumable bychemical reaction.

6. The battery of claim 4 wherein at least one of said switches is asolenoid.

2. The battery of claim 1 wherein said actuating means is coupled tosaid valve in a manner to vent gases evolved from said battery cell atpreselected voltage outputs.
 3. The battery of claim 1 wherein saidcontainer is shaped to entrap gases in its upper part adjacent saidaperture.
 4. The battery of claim 2 wherein said actuating meansincludes at least two electrically responsive switches.
 5. The batteryof claim 1 wherein said electrodes are consumable by chemical reaction.6. The battery of claim 4 wherein at least one of said switches is asolenoid.